1. Field of the Invention
The present invention relates to an infrared solid-state imaging device for detecting infrared light by means of two-dimensionally arrayed quantum-type semiconductor detecting section pixels, and particularly relates to an infrared solid-state imaging device provided with a compound semiconductor detecting section pixel or a type-II superlattice detecting section pixel, which necessarily contains Sb or In and consists of at least two elements out of elements Ga, Sb, In, As and Al.
2. Description of the Related Art
A quantum-type infrared solid-state imaging device has advantages of having high sensitivity and high-speed responsiveness since the quantum-type infrared solid-state imaging device treats infrared light as photons and uses mutual interaction between the photons and electrons in a semiconductor, and with those high sensitivity and high-speed responsiveness, the quantum-type infrared solid-state imaging device has been a key device in a variety of applications. Systems of this quantum-type infrared solid-state imaging device include an intrinsic system using a narrow band gap material capable of absorbing infrared light, and as the material, HgCdTe, InSb or the like being a compound semiconductor is used. Further, other systems recently attracting attention include a type-II superlattice system. In the type-II superlattice system, for example, a III-V group compound semiconductor system superlattice containing Sb, which is made up of thin layers of InAs and GaSb (or GaInSb), is formed on a GaSb substrate, and infrared light is absorbed through use of shifts between minibands which occur in the superlattice structure and between layers. A cutoff wavelength is adjustable from 3 to 25 μm, and the wavelength is adjustable not by means of a composition as in the HgCdTe intrinsic system, but by means of a film thickness. As compared to the HgCdTe intrinsic system, the type-II superlattice system has carriers with a larger effective mass, and with theoretically the same cutoff wavelength used, it is operated at a higher temperature by 30 K in a band with a wavelength of 10 μm and at a higher temperature by 10 K in a band with a wavelength of 3 to 5 μm. Further, since the type-II superlattice system can be applied with the III-V group compound semiconductor technique, it is expected to be manufactured more easily at lower cost as compared to the HgCdTe intrinsic system, and the type-II superlattice system is currently under active development. In a conventional quantum-type infrared solid-state imaging device having an intrinsic-system compound semiconductor detecting section or a type-II-superlattice-system detecting section, a groove (mesa) structure is formed and an insulating layer is embedded into the groove, to separate pixels (Manijeh Razeghi et. al. “State-of-the-art Type II Antimonide-based superlattice photodiodes for infrared detection and imaging”, Proc. of SPIE, Vol. 7467, pp. 74670T (FIGS. 4 and 7)).